Each holiday season the festivities in a notable minority of households are disrupted by flu. Typically infants and seniors are most at risk of severe illness, but occasionally a strain that disproportionately affects young and middle-aged adults emerges. Early evidence suggests 2013-2014 could be such a year.
The Centers for Disease Control and Prevention (CDC) received an unusually high number of reports of severe respiratory illness among young and middle-aged adults in the last two months of 2013. Many of the cases were linked to forms of H1N1, a virus strain that badly affected children and young adults in the 2009 swine flu pandemic. While it is too early in the season to conclude H1N1 will be the dominant strain in the 2013-2014 flu season, the CDC has seen enough evidence of its circulation to send a health notice to clinicians.
In the note the CDC reiterates its call for everyone aged 6 months and older to receive a flu vaccine. Patients have an unusual number of choices this year, with quadrivalent vaccines from AstraZeneca's ($AZN) biotech unit MedImmune, GlaxoSmithKline ($GSK) and Sanofi ($SNY) all available for the first time. The 2009 H1N1 pandemic also showed antiviral drugs, like Roche's ($RHHBY) Tamiflu, are effective. If a person at high-risk of complications catches the flu clinicians are advised to consider prescribing antivirals.
So far this flu season, severe H1N1-related illnesses have been most common among high-risk groups, such as pregnant women and the extremely obese. Several severe cases have occurred in people without these risk factors though. The flu season has hit Alabama, Louisiana, Mississippi, Missouri, Oklahoma and Texas hardest so far, but the CDC expects influenza viruses will spread across the U.S. in the coming weeks. As this happens, the CDC will look for genetic changes in H1N1 that suggest increased virulence or transmissibility.
- read the CDC notice